This invention relates generally to a printer which is small in size and more particularly, to a small sized ink jet type printer combining both electrical and manual operating procedures to assure extended operation with low power consumption. Ink jet printers of the ink-on-demand type require a small amount of energy for printing and hence, are advantageously operated by an internal battery. Such printers are used for portable printers such as an electronic desk top calculator. However, an ink jet printer has a disadvantage in that the nozzle end, having nozzles only several tens of microns in diameter, tends to become clogged with dried ink or with highly viscous ink. Such clogging renders the printer incapable of further operation. A conventional proposal for the prevention of nozzle clogging is to cover the front face, that is, discharge openings of the nozzles automatically with the aid of a solenoid when the printer is not used.
For complete elimination of nozzle clogging, it is necessary to hold the nozzle cover against the nozzle openings with considerable force. Such a large amount of force for pressing the nozzle cover against the nozzle openings is required also to prevent ink from flowing out of the nozzles when the portable printer is accidentally dropped and subjected to impact. Pocketsized calculator/printers must be carried without ink leakage also. Therefore, a relatively high level of energy is needed to properly cover the nozzle openings, thereby offsetting the advantage of low energy consumption for ejecting ink droplets for printing. In order to reliably press the nozzle cover against the nozzle openings, a drive source, such as a solenoid or an electrical motor, must be relatively large in size. As a result, the printer is costly to manufacture and not as small as is desirable.
What is needed is a an ink jet type printer which is protected against ink clogging and leakage without the consumption of large amounts of electrical energy or the use of large components.